Typewriter case shift mechanism



y 1959 J. P. BARKDOLL 2,896,766

I TYPEWRITER CASE SHIFT MECHANISM Filed Sept. 30, 1957 a Sheets-Sheet 1 JOSEPH P BARKDOLL BNVENTOR ATTQRNEY y 1959 J. P. BARKDOLL 2,896,766

TYPEWRITER CASE sum" MECHANISM' Filed Sept. 30,1957 3 Sheets-Sheet 2 JOSEPH P. BAR-KDOLL INVENTOR ATTORNEY July 28-, 1959 J. P. BARKDOLL TYPEWRITER CASE SHIFT MECHANISM 5 Sheets-Sheet 3 Filed. Sept. 30, 1957 FIG..4

JOSEPH P. BARKDOLL INVENTOR iii I ATTORNEY United States Patent 2,896,766 I V TYPEWRITER CASE SHIFT MECHANISM Joseph P. Barkdoll, Groton, N.Y., assignor to Smith- Corona Marchant Ina, Syracuse, N.Y., a corporation of New York Application September 30, 1957, Serial No. 686,926 I 16 Claims. (Cl. 197-74) This invention relates to improved case shift mechanism in a power operated typewriter and more particularly to such mechanism embodied in a typewriter having a continuously rotating toothed snatch roll.

The invention has for its principal objects to provide simple, compact and efiicient mechanism by which case shifting movement is imparted to the type bars; said movement from normal lower case position, to shifted upper case position is effected quickly but with a decelerating motion to prevent rebound; the case-shifted parts are cushioned against shock from rapid movement from one position to the other; and said parts are moved to said case-shifted position upon depression of a case shift key and maintained in said position until release of said key; all of which objects are accomplished with utmost economy of space and parts in a small, low, portable type- 'writing machine of this kind having a shiftable type bar segment supporting the type bars to strike upon the upper front quarter of the platen.

Other objects and advantages of the invention will appear from the following description of the illustrative embodiment thereof shown in the accompanying drawings, in which:

Figure l is'a top plan view of a typewriting machine equipped with a case shift mechanism embodying the invention, certain parts of the machine being omitted and others shown in broken lines for greater clarity of illustration of the case shift mechanism;

Figure 2 is a fragmentary vertical longitudinal sectional view of the rear portion of the machine on the line 2-2 of Figure l, the parts being shown in full line in their normal, lower case position, the upper case, shifted position of the parts being indicated by broken lines;

Figure 3 is an enlarged fragmentary sectional view of the forward portion of the machine on the line 3-3 of Figure l, the parts being shown in their normal position, and the latch support member being broken away for clarity;

Figure 4 is a view similar to Figure 3, the parts being shown in their shifted position;

Figure 5 is a fragmentary sectional view on the line 5-5 of Figure 3;

Figure 6 is a fragmentary sectional view on the line 66 of Figure 3; and

Figure 7 is a fragmentary sectional View of a portion of the latch'mechanism on the line 77 of Figure 5.

The drawings illustrate the invention as embodied in a power operated typewriting machine, similar to the Smith-Corona key operated portable typewriter, substantially as shown in United States patent to Avery Numbered 2,001,759, dated May 21, 1935, in which the main frame of the machine comprises side plates 10, a front end plate 11, and a rearwardly tilted cross plate 13, which supports a carriage, not shown, in which is journalled the platen 14. The type bars 16, only one being shown in Figure 2, are pivoted on a curved fulcrumwire in the slotted segment .17, which in turn is secured to a shift frame member 18 having forwardly projecting 45 2,896,766 Patented J uly 28, 1959 ICC cars 19 on either side. Brackets 20 secured to the cross plate 13 have similar forwardly projecting cars 21, and the ears 19 and 21 have slotted raceways 22 which cooperate with ball bearings 23 so that segment 17 is reciprocably movable toward and away from the platen 15.

Cross plate 13 and shift frame 18 are provided with projecting stop lugs, not shown, which cooperate to limit the movement of the segment 17 and shift frame 18 toward and away from the platen 15. The case shiftable parts 17 and 18 are spring biased, in a manner later described, to their upper, normal, lower case typing position, and may be shifted downwardly to their upper case typing position by means of a rock shaft 25 journalled in the side plates 10 forwardly of the segment 17.

The rock shaft 25 is provided with rearwardly projecting rock arms 26 welded thereto and the shift frame 18 is provided at either bottom corner with forwardly projecting ears 27 which bear transversely extending pivot screws 28 connecting the cars 27 with the rock arms 26, all as more fully described in the above-mentioned Patent 2,001,759..

The present invention comprises key-actuated. and power operated means for turning the rock shaft 25 to shift the segment 17 away from platen 15 and latch means for holding the case shifted parts in their lower,

upper case, shifted position as long as the case shift key is depressed. These means will now be described.

The rock shaft 25 is provided at its left end with a bellcrank lever 30 welded thereto. One arm 30a of bellcrank 30 has a biasing spring 31 secured to its projecting end and a similarly projecting arm 32 welded to the right-- hand end of shaft 25 has a similar spring 31 secured there'- to for biasing the case shift parts to their normal, lower case position. The forward ends of the springs 31 are secured to the transversely extending spring bar 33 which is fixed in the frame of the machine.

A curved rock shaft operating lever 35 is adjustably secured to the other arm 30b of the bellcrank 30 by means of clamping screws threaded into the bellcrank 30 through slotted holes in the operating lever 35. A forwardly projecting extension from the forward end of the operating lever 35 has a transversely turned tongue 35a at its forward end for a purpose hereinafter disclosed. The other end of lever 35 projects upward from shaft 25 and then forwardly and terminates in a portion 35b to which is- 'respondingly opposite end of the other plate, whereby the. plates 38 are mutually joined but longitudinally slidablel one with respect to the other. An extension spring 42 lies in the slots 39, one end being hooked into the hole 40 of one plate and the other end hooked into the hole 40 of the other plate. The link 36 is consequently longitudinally compressible but is normally extended to its full length by the spring 42. v

' One plate 38 at one end of the link 36 is pivotally secured to the portion 35b of the lever 35, as above described, and the other plate 38, at the other end of link 36, is similarly secured to the rearward portion 44a of an actuator lever 44, a shouldered screw 43 passing I through the plate 38 being threaded into the lever 44.

The actuator lever 44 is pivoted on a fulcrum wire 45 of a slotted cross bar 46 extending transverse the machine and secured to power side plates 47 which, in turn, are secured tothe side plates 10 of the machine as shown in Figure 1. One of a series of guide slots 48 in the cross bar 46, in which the actuator lever lies,"

serves to maintain the actuator lever 44 aligned, fore and I aft of the machine, with the end of the operating lever 35 of rock shaft 25. Actuator lever 44 is curved downwardly and rearwardly from its pivot around the adjacent toothed power roll, or snatch roll 50 which extends transversely across the machine. The roll 51) 1s journalled in the power side plates 47, and is continuously motor driven, by mechanism not shown, in the direction indicated by arrows in Figures 3 and 4, while the machine is operating. The portion 44a to which link 36 is secured extends upwardly above and to the rear of the snatch roll 50.

, The key-controlled means for actuating the movement of the actuator'lever 44 by interconnection with the snatch roll 50 is similar to that described inimy copending application Serial No. 686,925, filed September 30, 1957, describing the system of type bar actions, and therefore will now be but briefly described herein. An interponent pawl 51 is oscillatorily secured to the actuator lever 44, to the rear of the snatch roll 50, by means of a' shouldered rivet 52. The pawl 51 is normally adjacent to, but does not contact the snatch roll 50. A transversely turned tongue 51a on the upper portion of the pawl 51 has a hardened, forwardly projecting nose 51b normally adjacent to, but removed from, the path of the tips of the teeth on the snatch roll 50 as it rotates. The pawl 51, however, may be turned about its pivot 52, in a clockwise direction as viewed in Figures 3 and 4, so that the nose 51b is interposed in the path of the teeth of the roll 50. This turning of pawl 51 is limited in extent by a projection 51c conta cting the transversely bent tongue 44!) .on the rearward portion of actuator lever 44. A similar projec-.

tion' 51d on the pawl 51 and on the opposite side of the tongue 44b limits the turning of pawl 51 in the other direction and normally determines the position of the pawl on the actuator lever 44.

The forward end of the lower portion of pawl 51 is formed with a rounded notch or indentation 51a which cooperateswith the rounded end of an arm 53a of an actuator bellcrank lever 53 for turning the pawl 51 in either direction on its pivot. Bellcrank 53 is pivotally secured to the lower portion of the actuator lever 44 and also has a forwardly projecting arm 53b and a downwardly projecting tongue 530.

The actuator lever 44 also has a downwardly projecting tongue 44c, rearward of the actuator bellcrank 53, on which is pivotally secured the actuator pawl rocking cam 54. A spring 55 connects the cam 54 with the tongue 530 of the bellcrank so as-to bias a rounded nose 54a on the cam. against the lower edge of the pawl 51 and at the same time to urge the bellcrank 53 in a clockwise direction as viewed in Figures 3 and 4. The pawl 51 is consequently normally biased in a counterclockwise direction to its normal position on actuator lever 44 with the nose 51b out of contact with the snatch roll 50.

The lower edge of the pawl 51 is formed with a camming portion 51 immediately forward of the cam nose 54a and inclined upwardly therefrom. When the pawl 51 is turned clockwise as viewed in Figures 3. and 4, the nose 54a, of the cam, engages the camming edge 51 of the pawl and urges the pawl toward its engaged position with the stop pro'jectio'nSlc engaged with the stop tongue 44liiof the actuator lever 44. This will be understood by one familiar with the art to insure that the'pawl nose 51b enters the space between the teeth of the snatch roll 50 to the same extent on each occasion of operation.

, It will be apparent that the requirements for case shift power operation by means of a continuously operatirig power roll dilfer-from those fortype bar power operation in that latch means are required for securing thejcase shiftedparts in shifted position for periods ooend, actuator lever 44 has another downwardly projecting tongue 44d and, forwardly thereof, still another considerably shorter tongue 44a. A latch hook 56 is pivotally secured to the tongue 44d and a spring 57 connects the hook 56 to the tongue 44a providing upward bias to the forwardly extending hook.

The forward end of the latch hook 56 is guided in a slot 58a formed in a latch support 58 secured to the left hand power side plate 47 as plainly shown in Figures 5' and 7. 'The upper edge of the latch hook 56 is formed with a rearwardly facing shoulder 56a for engagement with a latch detent member 59 which is carried on the support 58, the book 56 being held in contact with detent member 59 by the spring 57. The detent member 5? is vertically oscillatable, being secured to the support 58 by a shouldered-rivet 60, as plainly shown in Figures 5 and 7, and has a forwardly facing shoulder 5% adjacent the rivet 66 adapted to be engaged by the shoulder 56a of the hook.

The forward end of the detent member 59 is slotted at 59b, the slot being open at its forward end and adapted to be engaged by va latch pin 61 carried by a portion of the case shift key lever mechanisrn now about to be briefly described.

' The typewriting machine is preferably provided with two case shift keys 62, one at either side of the keyboard, as shown in Figure 1. The keys 62 are each supported on a three armed keystem 63, the key being secured to a forwardly projecting arm 6311. Each keystem 63 is pivotally secured by a shouldered rivet '64 to an upper link 65 which, in turn, is pivotally secured in a slotted cross bar, preferably the same cross bar 46 which carries the actuator lever 44. The upper link 65 is a lever of cxtensivewith depression'of' the case shiftkey, To this.

the first order being pivoted on the fulcrum wire 66 and having a rearwardly projecting arm 65a.

The downwardly projecting arm 63b of each keystem is pivotally secured to a lower link, that on the left being denoted 67. Each lower link, in turn,.is pivoted on a fulcrum wire 68, also in the slotted cross bar 46; Arms 65a of the two upper links are connected across the keyboard by a conventional torsion rod 69 so that 'keys 62'Inove together substantially vertically up and down in the usual manner.

The third arm 636 of each keystem extends upwardly and rearwardly and has a transversely bent end projectmg downwardly to provide a down stop against the cross bar 46 when keys 62 are moved downward. The lower portion 63b of each keystem is provided with a forwardly projecting portion engaging the usual up-stop pad on a cross bar 70 secured to the sides of the machine.

The lower link 67,0n the left hand side of the machine only, is also a lever of the first order being provided with a rearwardly extending portion 67a to which is secured the usual return spring 71. The spring 71 biases the keystems 63 to their uppermost position and is secured at its other end to a cross bar 72 of a touch control mechanism not shown. The link 67 is also provided with an upwardly and rearwardly extending stop arm 6712 which, by engaging the cross bar 46, also limits 7 the downward movement of the keys 62.

The extension 67a ofthe left handlower link also acts as a trip lever, bearing thereon an actuator pawl trip member 73 which is pivotally secured thereto by the shouldered pin 61; previously referred to, the pin projectin'gtransversely from link 67 to engage the slot 5% The trip member 73 is end offarm 53 b of the bellcrank thereon as case shift key 62 is depressed and the portion 67a of the lower link is consequently raised. Trip member 73 is provided with astop 73b and is'biased' in a clockwise direction as' viewed in Figurest3'and 4 by the spring 74 so that-the lip' member may be'move'd aside by the arm 53b should the, actuator lever 44-return to its normal position for any reason prior to the return of the keys 62 and lower link 67, as more particularly shown and described in the aforementioned copending application Serial No. 686,925, filed September 30, 1957.

The left hand keystem 63 is also provided with a conventional locking key 75 secured to a lock keystem lever 76 pivotally secured to the upper arm 63c thereof at 77. A lower portion 7 6a of the lock lever 76 is provided with a hook 76b which is adapted to engage the end of a slot 78a in a lock member 78 secured to the cross bar 46, as shown in Figures 3, 4 and 6. A spring 79, secured to the lock lever 76at one end and to the cross bar 70 at the other, normally maintains the locking key 75 in raised position with the hook 76b disengaged from the lock member 78 in the usual manner.

In operation, depression of either of the case shift keys 62 or of the case shift lock key 75 depresses the forward end of the left hand lower link 67 and causes the corresponding elevation of the rearward portion 67a which bears the trip member 73. The upper portion 73a of the trip member engages the transversely turned tongue on the forwardly projecting arm 53b of the bellcrank lever 53 causing the counter-clockwise rotation of the bellcrank. Arm 53a of the bellcrank, being engageable in the notch 51e of the interponent pawl 51 causes the clockwise rotation of the pawl and the consequent engagement of its nose 51b with one of the teeth of the snatch roll 50. Since the stop 510 on the pawl engages with the stop 4412 on the actuator lever 44, the latter is forced downward about its pivot 45 until the snatch roll tooth rolls over, and out of engagement with the nose 51b of the pawl. As the actuator lever 44 moves downward, the projecting tongue 44d moves downward and forward carrying the latch hook 56 forward in its guide-slot 58a.

Upward movement of the lower link portion 67a also carries the pin 61 thereon upwardly and rearwardly and rotates the latch detent member 59 in a counter-clockwise direction on its pivot 60 from the position shown in Figure 310 that shown in Figure 4. It will be noted that in the latter position the shoulder 59a on the detent member is substantially aligned with the shoulder 56a of the latch hook and engaged therewith, the two parts being held in engagement by means of the spring 57.

As the actuator lever 44 moves downward, its rearward end 44a, carrying with it the forward end of the cushion link 36, moves downward and rearward, as indicated in Figure 4 from the position shown in broken line to that shown in full line.

Referring now to Figure 2, the movement of link 36 is indicated in that figure as being generally rearward from-the position shown in full line to that shown in broken line. It will be apparent that the rearward end of the link 36 is carried generally rearward and the lever 35 is turned in a counter-clockwise direction lowering the shift frame 18, the segment 17 and type bars 16 in the usual manner.

It will also be apparent that the movement of the actuator lever 44 on the link 36, from normal to case shifted position, is that of an unfolding toggled joint. A straight line A-A, shown partially in Figure 2 and partially in Figure 4 because of space limitations, drawn from the pivot 45 of actuator lever 44 to the case shifted position of the pivoted joint between lever 35 and link 36 passes just below the pivoted joint between actuator lever 44 and link 36, the knee joint of the toggle. It will be apparent, therefore, that the unfolding toggle 4436 approaches but does not quite unfold to a straight line, fully-extended position.

The transverse tongue'35a on the forwardly projecting arm of the rock shaft operating lever 35 contacts the link 36 in its case shifted position and constitutes a factory deformable stop bar adjustably controlling the proper action of the toggle.

It will now further be apparent that the entire unfolding action of the toggle 4436, as the parts are moved from normal to case shifted position, takes place over the range of toggle action closest to its straight-line position and that the action is one of deceleration. The advantages of this type of action are well known in the art, the novelty lying in the simplicity of design and economy of space and parts.

The shock-absorbing and rebound-preventing properties of the above described toggle action are augmented by the action of the cushion link 36. The sliding links 38,-being longitudinally movable, one with respect to the other, are held fully extended in normal position by the extension spring 42. Any initial shock occasioned by the sudden engagement of the nose 51b of the interponent pawl meeting with a tooth of the continuous rotating snatch roll 50 is absorbed by compression of the link 36. Furthermore, the action of stop 35a, being independent of the up and down stops associated with the 'case shift frame :18 and cross bar v13, permits the adjustment of parts for a slight compression of the link 36 in case shifted position to prevent rebound. The advantages of the novel construction of link 36, as described above, which permits the use of an extension spring in the thrust link required for the decelerating toggle action will be apparent to those familiar with the art.

The operation of the case shift mechanism upon return of the parts from case shifted to normal position will now be apparent. If the case shift lock has been utilized, a slight pressure on either of the case shift levers 62 will release the hook 76b from its engagement with the end of slot 78a, as shown in Figure 4, by operation of the spring 79.

Upon release of the case shift key 62, key levers 63 return to normal position and lower link 67 is rotated counterclockwise as viewed in Figures 3 and 4 by operation of the return spring 71. As the rearward portion of lower link 67 is lowered, pin 61 is carried downward and the latch detent member 59 is rotated clockwise about the rivet 60. This rotation of member 59 brings the nose at its lower forward end into contact with the upper edge of the forward end of latch hook 56, thus forcing the hook 56 down away from its latched position. As a result of the same rotation of member 59, the shoulder 59a is turned away from substantial alignment with shoulder 56a, thus. destroying the hooking action between the shoulders and permitting the ready escape of the hook 56 from its latched position. This action is facilitated by the location of shoulders 56a-59a, when in their latched position, quite close to the rivet 60, as shown in Figure 4. A difliculty frequently experienced with prior case shift mechanism has been that if the latching action is sufliciently positive, too much forcev is required for unlatching. The foregoing construction, in which unlatching may be said to be, practically speaking, self-energized, completely obviates this difliculty.

The actuator lever 44, being freed of the restraint of the latch 56-59, returns to its normal position through operation of the springs 31. It Will be noted that the pawl 51 and bellcrank 53 will already have returned to their rest positions on actuator lever 44 by operation of spring 55 as soon as the nose 51b rolled free of the engaged tooth of snatch roll 50 during the case shift stroke of the parts.

It will also be noted that the case shift return springs 31, by rotating the bellcrank arm 30a and rock shaft 25 in a clockwise direction, serve the double purpose of re- I claim: o

a 1. In a typewriting machine having a frame, a cojntin- '3 uously rotating power roll journalled in said frame, and an operation-effecting element reciprocal to a shifted position from and biased toward a normal stationary position thereof to perform its work; the combination with said element of means for moving said element from its normal stationary position including a rock shaft journalled in said frame, an operating arm radially secured to said rock shaft, a link havingone end pivotally secured to said operating arm, an actuator lever pivotally secured to the other end of said link member, the other end of said actuator lever being pivotally secured and guided in said frame transverse to said roll, an interponent pawl oscillatably carried on said actuator lever adjacent said roll and biased to a normal position on said actuator lever out of contact with said roll, saidlink and actuator lever comprising a normally partially folded toggle joint, and key operatedmeans for turning said pawl into engagement with said roll, whereby said toggle joint is straightened to move said element.

2. The combination as claimed in 'claim 1, including latch mechanism to hold said operation-effecting element in shifted position, comprising a latch member carried on said actuator, a second cooperating latch member pivotally secured to said frame, and means carried on said key operated means for turning said second latch member whereby said latch members are engaged upon operation of said key operated means and disengaged upon release thereof.

3. The combination as claimed in claim 1, including spring means operatively connected to said rock shaft for both biasing said operation effecting element to normal position and for returning said actuator lever to normal position. 7

4. The combination as claimed in claim ,1, including stop means carried by said rock shaft operating arm for preventing the complete straightening of said toggle joint,

The combination as claimed in claim 1, wherein said link comprises a cushion link having two parts slidably secured together and adapted to move longitudinally, one with respect to the other, and an extension spring each end of which is secured to a respective one of said parts to bias said'parts to fully extended relation each of said two parts being centrally slotted andsaid spring lying in said slots.

6. In a power operable case shift mechanism for a typewriter having a type bar segment reciprocal from and to normal, and case-shifted positions, a typewriter frame and a motor driven snatch roll, continuously rotating in said frame while said typewriter is in operation; means for shifting said segment comprising, in combination, an actuator lever pivotally secured at one end thereof and guided in said frame adjacent and transverse to said roll, a case shift operating lever, pivotally secured in said frame and operatively connected to said segment for movement thereof from and to normal and case shifted positions, spring means for biasing said lever and segment to'normal position, a link pivotally secured at one end to said actuator lever and at the other end to said operating leveiyan interponent pawl pivotally secured on said actuator lever for connecting said actuator lever to said roll and thereby moving said actuator lever away from said roll, said pawl being biased to a normal position out of contact with said roll, and key controlled means for moving said interponent, pawl into contact with said roll, said ke'y controlled means being spring biased to a normal rest position, said actuator lever and said link constituting a normally partially folded toggle adapted to be straightened by said movement of said actuator lever to shift said segment'from normal to shifted position.

7. The combination as claimed in claim 6, including a latch hookpivotally secured to said actuator lever, a latchdet ent member pivotally secured to said frame, spring means for biasing said hook into contact with said detent member, said'spring means being carried on said actuator lever, and a latch pinsecured to said key 8 controlled means and engaged with said detent member whereby said detent member is turned in one direction to engage said hook when said key controlled means is operated and turned in the other direction to release said hook when said key operated means returns to norrnal rest position. 7 a 8. In a power operated typewriting' machine having a frame and a continuously rotating snatch roll; case shift mechanism comprising, in combination, a part to be shifted, a case shift key, an actuator lever pivotally secured and guided in said frame transverse to said roll, said actuator lever being operatively connected to said part to be shifted, an interponent member carried on said actuator lever and being movable thereon for engagement with said roll for moving said actuator lever I away from said roll, means operated by said key' and spring biased to a normal raised key position, for moving said interponent member into engagement with said roll, a latch hook carried on said actuator lever, a latch detent member oscillatably secured to said frame, spring means for biasing said hook into contact with said detent member and a latch pin engaging said detent member for oscillation thereof, said pin being carried on said key operated means whereby said detent member is adapted to 'engage with said hook when said key is depressed and to disengage from said hook when the key is released. I

9. In a power operable case shift mechanism for a typewriter having a frame and a continuously rotating snatch roll journalled in said frame; the combination of a part to be shifted, a case shift key, an actuator lever pivoted in said frame and having a spring biased normal position adjacent said roll, an interponent member oscillatably secured to said actuator lever and adapted to be moved into engagement with said roll for moving said actuator lever away from said roll to a shifted position, means operated by said key for turning said interponent member into engagement with said roll, a link member pivotally secured to said actuator lever and forming an operative decelerating toggle joint therewith, said link member being operatively connected to the part to be shifted, a latch hook secured to said actuator lever, a latch detent member oscillatably secured to said frame and adapted to engage said hook when said actuator lever is in shifted position, and a latch pin secured to said key operated means and engaging said detent member whereby said detent member is disena key.

10. In a power operable case shift mechanism for a typewriter having a frame and a continuously rotating snatch roll journalled in said frame; the combination of a part to be shifted, a case shift key, an actuator lever oscillatably secured and guided in said frame transverse to said roll, means operatively connecting said actuator lever with said part to be shifted, spring means for biasing said actuator lever to a normal position adjacent said roll, an interponent pawl oscillatably secured to said actuator lever and spring biased to a rest position out of contact with said roll, a bellc rank oscillatably secured to said actuator lever and adapted to turn said interponent pawl into engagement with said roll, key supporting means, including apivoted trip lever, for supporting said case shift key, said key being springbiased upwardly to a rest position, and a trip-member on said trip lever adapted to operatively engage said bellcrank when said key is depressed whereby said bellcrank and interponent pawl are turned 'and'said' actuator lever and said part to be shifted are moved by said roll to shifted position. i V

11. inc said trip member is pivoted on said trip lever and spring biased to a rest position on said lever for contacting, said bellcrank whereby said trip-memh'eris adapted to be cammed aside by said bellcrank when said actuator combination as claimed in claim 10, wherein lever precedes said trip lever to their respective rest positions.

12. The combination as claimed in claim 10, including an interponent pawl cam pivotally secured to said actuator lever and spring biased into contact with said pawl, said pawl having a camming edge adapted to be contacted by said cam when said pawl is turned toward its position of engagement with said roll whereby full engagement with said roll by said pawl is insured.

13. The combination claimed in claim 10, including a link pivotally secured to said actuator lever, said link and said actuator lever constituting a toggle joint normally partially folded and adapted to be straightened by the engagement of said interponent pawl with said roll for shifting said part.

14. The combination as claimed in claim 10, including a latch hook carried on said actuator lever, a latch detent member oscillatorily supported on said frame and adapted to engage said hook, a latch pin carried on said trip lever and operably engaged with said detent member,

said detent member being turned in one direction when said case shift key is depressed and turned in the other direction when said key is released whereby said hook is engaged with and restrained by said detent member when said key is depressed and said actuator lever is in shifted position and said hook is disengaged from said detent member when said key is released.

15. In a typewriting machine having an operationefifecting element reciprocal to and from a normal stationary position; the improvement comprising means for moving said element from its normal stationary position including a cushioning thrust link comprising two identical parts slidably secured together and adapted to move longitudinally, one with respect to the other, and an extension spring, each end of which is secured to a respective one of said identical parts to bias said parts to fully extended relation, each of said two parts being centrally slotted and said spring lying in said slots.

16. In a power operable case shift mechanism for a typewriter having a frame, a continuously rotating power roll, a part to be shifted, an actuator lever pivotally secured and guided in said frame and operatively connected to said part to be shifted, interponent means carried on said actuator lever and adapted to engage said roll for moving said lever and said part to be shifted, a case shift key, and case shift key cont-rolled means for moving said interponent means into engagement with said roll; latch means comprising a hook carried on said actuator lever, a detent member carried on said frame and adapted to engage with and restrain said hook, and a pin carried on said key controlled means, said hook being spring biased toward contact with said detent member, said pin being engaged with said detent member for rotation thereof in one direction to latched position when said case shift key is depressed and for rotation thereof in the other direction to unlatched position when said key is released.

References Cited in the file of this patent UNITED STATES PATENTS 2,590,777 Kupper May 25, 1952 2,631,713 Hill Mar. 17, 1953 2,675,112 Helmond Apr. 13, 1954 

